You’re exactly right… massive amounts of both matter and antimatter were created when the universe was born. This matter combined with the antimatter and wiped eachother out, generating the energy which caused the universe to grow. Like you say, there was a wee bit more matter than antimatter and that’s what’s made us and everything we know around us.
It was predicted that matter and antimatter should have completely obliterated one another and therefore technically, we shouldn’t be here. And yet, here I am writing to you now. Hello! *waves*
Now this isn’t my area of science but it’s something I’m interested in. There’s only a tiny bit more matter than antimatter (something daft like 50.00000000000000001% to 49.999999999999999999%). Scientists are now trying to work out why we’re here and why there was more matter. Perhaps there’s a difference in the way matter and antimatter behaves? Or maybe there’s a bunch of antimatter floating about somewhere? 🙂
Mark’s research is exactly in this area, so I will let him tell you what he has found out. But one thing to think about is that we base all our theories on what we can observe, and the conditions right at the moment of the big bang are very hard (if not impossible) to recreate. So we don’t yet know, and can’t really measure what happened then, or why.
This is one of the biggest questions in particle physics – we don’t know. It is believed that there were additional forces (in addition to the 4 we know now) in first few minutes of the universe and these forces acted differently on matter and anti-matter and this also requires new particles to exist – this is what the LHC is looking for – for example super-symmetric particles. It is also believed there were heavy (unstable) neutrinos around at the start of the universe and these didn’t decay equally into matter and anti-matter – at the moment this is all speculation we need to produce some of these particles in an accelerator to give them any credibility…